Article
Chemistry, Physical
Mina Zhang, Xianglin Zhou, Dafeng Wang, Longjun He, Xuyang Ye, Wenwu Zhang
Summary: The application scope and market demand for additive-manufactured high-entropy alloys (AM HEAs) have broadened of late. A dual-phase AlCoCuFeNi HEA was fabricated by selective electron beam melting (SEBM) with superior compressive strength and ductility. Further improvements were achieved using selective electron beam remelting (SEB-RM) during SEBM, resulting in better compressive properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Nanoscience & Nanotechnology
Samuel Milton, Olivier Rigo, Sebastien LeCorre, Antoine Morandeau, Raveendra Siriki, Philippe Bocher, Rene Leroy
Summary: Additive Manufacturing (AM) processes like Selective Laser Melting (SLM) and Electron Beam Melting (EBM) were used to fabricate Ti6Al4V parts, and the machining behavior of these parts was studied. The microstructure and mechanical properties of the material were found to be strongly influenced by the type of AM process and subsequent heat treatment, impacting the machinability of the parts.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Hangyu Yue, Hui Peng, Kesong Miao, Boyang Gao, Hao Wu, Jibang Yang, Guohua Fan
Summary: In this study, the effect of adding 0.2 wt% Y2O3 nanoparticles on the microstructure and elevated-temperature tensile properties of TiAl alloy prepared by selective electron beam melting (SEBM) was investigated. The results showed that the addition of nano-Y2O3 particles induced the formation of dislocations and twins, resulting in an increase in the density of geometrically necessary dislocations. The ultimate tensile strength and fracture elongation of Ti-48Al-2Cr-2Nb-0.2Y2O3 improved at high temperatures compared to Ti-48Al-2Cr-2Nb alloy. The strengthening mechanism attributed to the added Y2O3 nanoparticles was also discussed. These findings provide valuable insights for enhancing the high-temperature mechanical properties of TiAl alloys.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Chemistry, Physical
Hangyu Yue, Hui Peng, Ruifeng Li, Runqi Gao, Xiaopeng Wang, Yuyong Chen
Summary: This study investigated the high-temperature microstructure stability of TiAl alloys fabricated by electron beam smelting (EBS) and selective electron beam melting (SEBM). The results showed that annealing temperature significantly affected the microstructure and fracture toughness of the alloys.
Article
Nanoscience & Nanotechnology
Hangyu Yue, Zhenquan Liang, Feng Zhang, Lijia Fang, Pei Chen, Lijuan Xu, Shulong Xiao, Ruifeng Li
Summary: This study investigated the effect of heat treatment on the microstructure and creep behavior of Ti-48Al-2Cr-2Nb alloy prepared by selective electron beam melting. The results showed that heat treatment significantly improved the creep properties of the alloy and increased the creep rupture life. The creep fracture behavior also varied between the as-built and heat-treated alloys.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Hangyu Yue, Hui Peng, Guohua Fan, Jibang Yang, Hao Chen, Xuewei Fang
Summary: The effects of beam speed on the microstructure, defects, and mechanical properties of Ti-48Al-2Cr-2Nb alloy with nano-Y2O3 addition were studied. The orientation relationship between nano-Y2O3 and the matrix was determined. The Y2O3-bearing TiAl alloys exhibited excellent compressive properties at room temperature, showing potential for applications.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Chemistry, Physical
Bing Wei, Zuming Liu, Bizhong Nong, Bin Cao, Xueqian Lv, Yake Ren, Yongkang Ai
Summary: Selective laser melting (SLM) was used to prepare Rene 104 PM nickel-based superalloy samples, which exhibited unique microstructure and cracking behavior, resulting in significant anisotropy in tensile performance.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Engineering, Manufacturing
Yang Li, Wenbin Kan, Yanming Zhang, Mingzhi Li, Xiaoyu Liang, Yefeng Yu, Feng Lin
Summary: This study successfully prepared IN738LC superalloy specimens using Electron Beam Selective Melting, established a defect-free criterion, and determined a processing window with a proper energy density. The research identified the strengthening and fracture mechanisms of critical size gamma' phases and carbides at different temperatures, as well as different fracture mechanisms in PBD and OBD specimens through tensile tests and fractographic analyses.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Yang Yang, Jianlin He, Junyi Huang
Summary: The adiabatic shear behavior of Ti-6Al-4V alloy manufactured by selective electron beam melting (SEBM) was studied. The effects of microstructure, phase composition, and crystal orientation on adiabatic shear behavior were investigated. The results showed that heat treatment significantly reduced the anisotropy of the alloy and increased its susceptibility to adiabatic shearing. The as-printed longitudinal samples were more prone to adiabatic shearing than the radial samples, and the heat-treated samples exhibited increased adiabatic shear susceptibility due to changes in the microstructure and alpha phase thickness.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Hang-Yu Yue, Hui Peng, Yong-Jun Su, Xiao-Peng Wang, Yu-Yong Chen
Summary: The microstructure and high-temperature tensile properties of a Ti-47Al-2Cr-2Nb alloy fabricated via selective electron beam melting with different hatch spacings were systematically investigated. The alloy showed changes in microstructure and grain morphology with increasing hatch spacing. The alloy fabricated with a spacing of 100 mu m exhibited the highest tensile strengths at both room temperature and 700 degrees C.
Article
Nanoscience & Nanotechnology
Sijia Wang, Jixin Yang, Jianfei Sun, Wenxiang Shu, Haibin Yang, Alfonso H. W. Ngan, Yongjiang Huang
Summary: Here, TA15 samples near alpha titanium alloy were fabricated using electron beam selective melting (EBSM), and their high-temperature tensile deformation behaviors were studied. The results showed that the samples exhibited work hardening and softening at different temperatures, and the EBSM-built TA15 samples had excellent mechanical properties at medium temperatures. These findings are helpful for the industrial applications of EBSM-built titanium alloy components in the aerospace fields.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Bang Xiao, Wenpeng Jia, Jian Wang, Lian Zhou
Summary: FeCoCrNi- and WMoTaNb-based alloys are two prevalent high-entropy alloy systems. Additive manufacturing is widely employed in forming these alloys due to its superiority of complex shape forming and flexible materials design, which can meet the diverse demands for refractory alloy.
MATERIALS CHARACTERIZATION
(2022)
Article
Engineering, Manufacturing
Igor Drstvensek, Franc Zupanic, Tonica Boncina, Tomaz Brajlih, Snehashis Pal
Summary: This research investigated the geometry, microstructure, and tensile properties of Ti-6Al-4V samples produced by Selective Laser Melting (SLM) and Electron Beam Melting (EBM). The EBM samples built up in the Z-direction had the lowest yield strength and the highest elongation due to the slowest cooling rate, promoting continuous dynamic recrystallization. The study identified two new ? colonies in the samples, showing significant variations in size and orientation between the core and surface zones.
JOURNAL OF MANUFACTURING PROCESSES
(2021)
Article
Materials Science, Multidisciplinary
Jiawen Feng, Wanyuan Gui, Qian Liu, Wenya Bi, Xuechong Ren, Yongfeng Liang, Junpin Lin, Benli Luan
Summary: In this study, the electron beam selective melting (EBM) technique was used to shape Ti-48Al-2Cr-2Nb alloy, resulting in high-density samples. The mechanism of phase transformation and microstructural evolution as well as the interaction with tensile properties were investigated. The EBM-formed Ti-48Al-2Cr-2Nb alloy exhibited a unique microstructure and superior mechanical properties.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Crystallography
Jiangtao Ran, Xiaojing Sun, Shiliang Wei, Zhuo Chen, Hong Zhao
Summary: This study focused on the effects of extracted position and characterization direction on the microstructure, defect distribution, and Vickers hardness of TA15 titanium alloy fabricated by electron beam melting. Results showed differences in microstructure, defect distribution, and density between longitudinal and transversal directions, providing important insights for optimizing manufacturing processes.
Correction
Chemistry, Physical
Fang Luo, Aaron Roy, Luca Silvioli, David A. Cullen, Andrea Zitolo, Moulay Tahar Sougrati, Ismail Can Oguz, Tzonka Mineva, Detre Teschner, Stephan Wagner, Ju Wen, Fabio Dionigi, Ulrike I. Kramm, Jan Rossmeisl, Frederic Jaouen, Peter Strasser
Article
Chemistry, Applied
Divakar R. Aireddy, Amitava Roy, David A. Cullen, Kunlun Ding
Summary: Supported Na-Mn-W oxides on titanate nanowires were found to have similar catalytic performance as the commonly studied MnOx/Na2WO4/SiO2 catalyst, with a synergistic effect between MnOx and WOx sites. The titanate support not only acts as a reservoir for alkali metals, but also stabilizes isolated MnOx species, contributing to the high selectivity toward C2+ products and suppressed COx formation.
Article
Chemistry, Physical
Luigi Osmieri, Yanghua He, Hoon T. Chung, Geoffrey McCool, Barr Zulevi, David A. Cullen, Piotr Zelenay
Summary: Anion exchange membrane water electrolysis is an attractive technology for low-cost generation of green hydrogen by combining the use of noble metal-free catalysts with pure water feed. By addressing drawbacks of other electrolysis technologies, it has the potential to replace them.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Xiang Lyu, Tim Van Cleve, Erica Young, Jianlin Li, Haoran Yu, David A. Cullen, K. C. Neyerlin, Alexey Serov
Summary: Proton exchange membrane fuel cells (PEMFCs) powered by green hydrogen (H2) are a promising alternative to traditional hydrocarbon-fueled power generators. However, further improvements are needed in efficiency, durability, and low-cost production for widespread adoption. Most strategies to improve PEMFC electrodes utilize single material sets, but anisotropic electrode structures with locally tunable properties may offer enhanced performance due to improved transport.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Leiming Hu, Tim Van Cleve, Haoran Yu, Jae Hyung Park, Nancy Kariuki, A. Jeremy Kropf, Rangachary Mukundan, David A. Cullen, Deborah J. Myers, K. C. Neyerlin
Summary: The degradation of polymer electrolyte membrane fuel cells (PEMFCs) catalyst layers for heavy-duty vehicles was studied using a catalyst-specific accelerated stress test (AST). The PtCo/HSC catalyst showed better initial mass activity, larger initial mass transport loss, and faster degradation compared to a-Pt/HSC and Pt/HSC catalysts. Pt dissolution resulted in ECSA losses, either by catalyst particle growth or redeposition in the membrane.
JOURNAL OF POWER SOURCES
(2023)
Article
Electrochemistry
Kaur Muuli, Xiang Lyu, Marek Mooste, Maike Kaarik, Barr Zulevi, Jaan Leis, Haoran Yu, David A. Cullen, Alexey Serov, Kaido Tammeveski
Summary: In this study, Fe-N-C catalysts were prepared at a kilogram scale using the commercial VariPoreTM method, and the effect of synthesis conditions on the catalyst performance at ZAB air electrode was investigated. The results showed that the PA-450-HT catalyst exhibited excellent electrocatalytic activity for the oxygen reduction reaction (ORR) and was the most suitable catalyst for primary ZAB, with a galvanostatic polarization discharge peak power density of 149 mW cm-2, outperforming commercial Pt-Ru/C catalysts. Additionally, the NCB-600-HT catalyst displayed outstanding ORR and OER reversibility, with a half-wave potential of 0.87 V vs. RHE and a Delta E value of 0.81 V, and exhibited excellent charge-discharge cycling durability similar to NCB-550-LT for the secondary ZAB. This study reported for the first time the mass production of outstanding bifunctional Fe-N-C catalysts for rechargeable ZAB.
ELECTROCHIMICA ACTA
(2023)
Article
Chemistry, Physical
Kevin D. Sisco, Alex Plotkowski, Ying Yang, Larry Allard, Chris Fancher, Claudia Rawn, Jonathan D. Poplawsky, Ryan Dehoff, S. S. Babu
Summary: Heat treatment of additively manufactured Al-Ce based multicomponent alloys leads to complex micro-structure evolution. The study explores the phase transformation theories involving nucleation from a heterogeneous multi-phase microstructure typical to that of additively manufactured samples. Different solidification microstructures were obtained due to spatial and temporal variations of thermal gradients (G) and liquid-solid interface velocities (R) within a given melt pool. The phase transformation pathways are rationalized based on the role of driving force on the nucleation of different phases at the interface of aluminum and the non-equilibrium intermetallic phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Physics, Applied
K. D. Koube, T. Sloop, K. Lamb, J. Kacher, S. S. Babu, N. N. Thadhani
Summary: This study investigates spall failure and damage modes in Laser Powder Bed Fusion fabricated Stainless Steel 316L (SS316L) with intentional low-volume porosity. The results show that the suppression of spall failure is observed with increasing porosity, transitioning from spall-centered tensile stress dominated failure to a pore-centered microstructure-dominated damage mode involving void/crack nucleation and growth. The critical porosity level and spall location depend on both the volume fraction and the size of the initially fabricated pores. Heterogeneous deformation twinning, shear banding, grain rotation, and cracking are observed around pre-existing pores and expected spall failure sites.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
D. P. Leonard, S. Komini Babu, J. S. Baxter, H. M. Meyer, D. A. Cullen, R. L. Borup
Summary: The high production cost of gas diffusion layer (GDL) in proton exchange membrane fuel cells is mainly due to the use of polyacrylonitrile (PAN) fibers. This study examines the performance of inexpensive natural fiber-based papers and fabric as GDLs, and the improvements achieved by incorporating a microporous layer, gas-phase hydrophobic treatment, and densification. The resulting GDLs demonstrate comparable performance to the commercial baseline GDL and highlight the potential of reducing GDL manufacturing costs.
JOURNAL OF POWER SOURCES
(2023)
Article
Nanoscience & Nanotechnology
Arunima Banerjee, Jeff Rossin, Mo-Rigen He, William D. Musinski, Paul A. Shade, Marie E. Cox, Edwin J. Schwalbach, Tresa Pollock, Kevin J. Hemker
Summary: This study investigates the influence of build orientation-induced texture and geometric effects on the mechanical response of thin-walled Inconel 625 (IN625) T-elements fabricated by laser-based powder bed fusion. The results show that the differences in build orientation and geometry significantly affect the elastic response of the components. These findings are important for understanding the performance of 3D printed thin-walled structures under complex loading conditions.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Electrochemistry
Xiang Lyu, Dimitra Anastasiadou, Jithu Raj, Jingjie Wu, Yaocai Bai, Jianlin Li, David A. Cullen, Jun Yang, Liliana P. L. Gonsalves, Oleg I. Lebedev, Yury V. Kolen'ko, Marta Costa Figueiredo, Alexey Serov
Summary: A facile approach for synthesizing M-N-C catalysts (M = Co, Fe, Ni) without organic solvents at a commercial scale is reported. Single atomic catalysts with high surface areas were successfully obtained. Among the synthesized catalysts, Ni-N-C exhibited the highest performance in the electrochemical CO2 reduction reaction, with 80% Faradaic efficiency of CO production at -0.49 VRHE and a turnover frequency of 57,379 h-1. The large-scale synthesis and high performance of M-N-C catalysts enable their practical implementation in industrially relevant CO2RR.
ELECTROCHIMICA ACTA
(2023)
Article
Materials Science, Multidisciplinary
J. David Arregui-Mena, Philip D. Edmondson, David Cullen, Samara Levine, Cristian Contescu, Yutai Katoh, Nidia Gallego
Summary: In the 1960s, the feasibility of molten salt reactors for civil applications was demonstrated by the Molten Salt Reactor Experiment using CGB graphite as the fast neutron moderator. Additional impregnation steps were taken to reduce molten salt ingression, but little information has been published about the microstructure or sealant of this graphite grade. The study presents advanced microscopy results and investigates the sealing technology of legacy material from the Molten Salt Reactor Experiment, providing insights for potential reutilization in modern reactors.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Peter C. Metz, Zach Arwood, Cole Franz, Eric Heikkenen, Vivek Chawla, Sudarsanam Suresh Babu, Dayakar Penumadu, Katharine Page
Summary: Evaluation of Ti-6Al-4V material deposited by AFSD on rolled Ti-64 base plate revealed different stress-strain responses between base plate and AFSD regions. Microstructure gradients observed by optical microscopy and spatially resolved PXRD rationalized these differences. AFSD regions exhibited a characteristic basket weave α-Ti microstructure, while the base plate showed a globular α+6 microstructure. Control of prior 6 microstructure using targeted deposition parameters will be critical for achieving desired properties using AFSD with titanium alloys.
Article
Nanoscience & Nanotechnology
Kui Li, Lei Ding, Zhiqiang Xie, Gaoqiang Yang, Shule Yu, Weitian Wang, David A. Cullen, Harry M. Meyer III, Guoxiang Hu, Panchapakesan Ganesh, Thomas R. Watkins, Feng-Yuan Zhang
Summary: Electrochemical conversion of nitrogen to green ammonia is hindered by the lack of efficient electrocatalysts. In this study, a cost-effective bimetallic Ru-Cu mixture catalyst in a nanosponge architecture was designed. The optimized Ru0.15Cu0.85 NS catalyst exhibited impressive N2RR performance and superior stability, surpassing monometallic Ru and Cu nanostructures. This work contributes to the design of efficient electrocatalysts for ambient electrochemical ammonia production.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Engineering, Manufacturing
Nathaniel Wood, Edwin Schwalbach, Andrew Gillman, David J. Hoelzle
Summary: This study reports the measurement of input signals, output signals, and structural data for eight IN 718 samples during laser powder bed fusion (PBF) process. The data from multiple samples improve the statistical replicability of the measurements. The main result is an open and comprehensive data set for validating PBF process and structure models.
INTEGRATING MATERIALS AND MANUFACTURING INNOVATION
(2023)
